Fix padding_idx=None handling in aten_embedding_bag_padding_idx

[Copilot]

The aten_embedding_bag_padding_idx function was failing when PyTorch passed padding_idx=None, which is a valid value according to PyTorch's API specification. The function had an assertion that explicitly prevented None values, causing export failures.

Changes Made

1. Updated function signature: Changed padding_idx: int = -1 to padding_idx: Optional[int] = -1 to properly reflect PyTorch's API where padding_idx can be None

2. Removed blocking assertion: Removed assert padding_idx is not None that was preventing valid None values

3. Added proper None handling: When padding_idx is None, the function now delegates to the regular aten_embedding_bag function, which matches PyTorch's behavior where padding_idx=None is equivalent to no special padding handling

Example

Before this fix, the following would fail with an AssertionError:

# This would raise: "padding_idx must not be None. This is likely a dispatcher error"
torch.ops.aten.embedding_bag.padding_idx(weight, indices, offsets, padding_idx=None)

After the fix, it works correctly by falling back to regular embedding_bag behavior when padding_idx=None.

The fix is minimal and surgical, maintaining full backwards compatibility for existing integer values of padding_idx while enabling the previously unsupported None case.

Fixes #2145.

---

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[codecov]

❌ 3 Tests Failed:

Tests completed	Failed	Passed	Skipped
15725	3	15722	1697

View the top 3 failed test(s) by shortest run time

onnxscript.backend.onnx_export_test.TestOnnxBackEnd::test_export2python_produces_correct_onnx_script_model_0125_test_ai_onnx_ml_tree_ensemble_set_membership

Stack Traces | 0.009s run time

onnxscript/converter.py:460: in _eval_constant_expr
    return eval(cpl, self.globals, locals)  # pylint: disable=eval-used
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
E   NameError: name 'nan' is not defined

The above exception was the direct cause of the following exception:
..../test_ort_nightly/lib/python3.11.../site-packages/parameterized/parameterized.py:620: in standalone_func
    return func(*(a + p.args), **p.kwargs, **kw)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/backend/onnx_export_test.py:271: in test_export2python_produces_correct_onnx_script_model
    functions = extract_functions(backend_test.name, code, self.test_folder)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/backend/onnx_export_test.py:137: in extract_functions
    mod = importlib.import_module(import_name)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.../Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/importlib/__init__.py:126: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
<frozen importlib._bootstrap>:1204: in _gcd_import
    ???
<frozen importlib._bootstrap>:1176: in _find_and_load
    ???
<frozen importlib._bootstrap>:1147: in _find_and_load_unlocked
    ???
<frozen importlib._bootstrap>:690: in _load_unlocked
    ???
..../test_ort_nightly/lib/python3.11.../_pytest/assertion/rewrite.py:186: in exec_module
    exec(co, module.__dict__)
tests/onnx_backend_test_code/test_ai_onnx_ml_tree_ensemble_set_membership.py:9: in <module>
    @script()
     ^^^^^^^^
onnxscript/main.py:94: in transform
    result = script_check(f_ast, opset, env, src, default_opset=default_opset)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/main.py:38: in script_check
    return convert.translate_function_def(f)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:1452: in translate_function_def
    fn_ir = self._translate_function_def_common(stmt)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:1439: in _translate_function_def_common
    self._translate_stmt(s, index_of_stmt=i)
onnxscript/converter.py:961: in _translate_stmt
    return self._translate_assign_stmt(node)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:1048: in _translate_assign_stmt
    assign(lhs, rhs)
onnxscript/converter.py:992: in assign
    t = self._translate_expr(rhs, lhs).name
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:546: in _translate_expr
    r = self._translate_call_expr(node)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:825: in _translate_call_expr
    attrs = [
onnxscript/converter.py:826: in <listcomp>
    self._translate_attr(x, y, callee.op_schema.attributes[x])
onnxscript/converter.py:510: in _translate_attr
    val = self._eval_constant_expr(expr)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:462: in _eval_constant_expr
    raise NameError(
E   NameError: ERROR: Missing names, globals contains ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__file__', '__cached__', '__builtins__', '@py_builtins', '@pytest_ar', 'numpy', 'TensorProto', 'make_tensor', 'script', 'external_tensor', 'Opset', 'FLOAT', 'ai_onnx_ml5'], locals [].
E   at: Function 'bck_test_ai_onnx_ml_tree_ensemble_set_membership', line 3
E       Y = ai_onnx_ml5.TreeEnsemble(X, aggregate_function=1, leaf_targetids=[0, 1, 2, 3], leaf_weights=make_tensor("value", 1, dims=[4], vals=[1.0, 10.0, 1000.0, 100.0]), membership_values=make_tensor("value", 1, dims=[8], vals=[1.2000000476837158, 3.700000047683716, 8.0, 9.0, nan, 12.0, 7.0, nan]), n_targets=4, nodes_falseleafs=[1, 0, 1], nodes_falsenodeids=[2, 2, 3], nodes_featureids=[0, 0, 0], nodes_modes=make_tensor("value", 2, dims=[3], vals=[0, 6, 6]), nodes_splits=make_tensor("value", 1, dims=[3], vals=[11.0, 232344.0, nan]), nodes_trueleafs=[0, 1, 1], nodes_truenodeids=[1, 0, 1], post_transform=0, tree_roots=[0])
E                                                                                                                                                                                             ^

onnxscript.backend.onnx_export_test.TestOnnxBackEnd::test_export2python_produces_correct_onnx_script_model_0904_test_ai_onnx_ml_tree_ensemble_set_membership

Stack Traces | 0.017s run time

onnxscript/converter.py:460: in _eval_constant_expr
    return eval(cpl, self.globals, locals)  # pylint: disable=eval-used
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
E   NameError: name 'nan' is not defined

The above exception was the direct cause of the following exception:
..../test_ort_nightly/lib/python3.11.../site-packages/parameterized/parameterized.py:620: in standalone_func
    return func(*(a + p.args), **p.kwargs, **kw)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/backend/onnx_export_test.py:271: in test_export2python_produces_correct_onnx_script_model
    functions = extract_functions(backend_test.name, code, self.test_folder)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/backend/onnx_export_test.py:137: in extract_functions
    mod = importlib.import_module(import_name)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.../hostedtoolcache/Python/3.11.12.../x64/lib/python3.11/importlib/__init__.py:126: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
<frozen importlib._bootstrap>:1204: in _gcd_import
    ???
<frozen importlib._bootstrap>:1176: in _find_and_load
    ???
<frozen importlib._bootstrap>:1147: in _find_and_load_unlocked
    ???
<frozen importlib._bootstrap>:690: in _load_unlocked
    ???
..../test_ort_nightly/lib/python3.11.../_pytest/assertion/rewrite.py:186: in exec_module
    exec(co, module.__dict__)
tests/onnx_backend_test_code/test_ai_onnx_ml_tree_ensemble_set_membership.py:9: in <module>
    @script()
     ^^^^^^^^
onnxscript/main.py:94: in transform
    result = script_check(f_ast, opset, env, src, default_opset=default_opset)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/main.py:38: in script_check
    return convert.translate_function_def(f)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:1452: in translate_function_def
    fn_ir = self._translate_function_def_common(stmt)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:1439: in _translate_function_def_common
    self._translate_stmt(s, index_of_stmt=i)
onnxscript/converter.py:961: in _translate_stmt
    return self._translate_assign_stmt(node)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:1048: in _translate_assign_stmt
    assign(lhs, rhs)
onnxscript/converter.py:992: in assign
    t = self._translate_expr(rhs, lhs).name
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:546: in _translate_expr
    r = self._translate_call_expr(node)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:825: in _translate_call_expr
    attrs = [
onnxscript/converter.py:826: in <listcomp>
    self._translate_attr(x, y, callee.op_schema.attributes[x])
onnxscript/converter.py:510: in _translate_attr
    val = self._eval_constant_expr(expr)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript/converter.py:462: in _eval_constant_expr
    raise NameError(
E   NameError: ERROR: Missing names, globals contains ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__file__', '__cached__', '__builtins__', '@py_builtins', '@pytest_ar', 'numpy', 'TensorProto', 'make_tensor', 'script', 'external_tensor', 'Opset', 'FLOAT', 'ai_onnx_ml5'], locals [].
E   at: Function 'bck_test_ai_onnx_ml_tree_ensemble_set_membership', line 3
E       Y = ai_onnx_ml5.TreeEnsemble(X, aggregate_function=1, leaf_targetids=[0, 1, 2, 3], leaf_weights=make_tensor("value", 1, dims=[4], vals=[1.0, 10.0, 1000.0, 100.0]), membership_values=make_tensor("value", 1, dims=[8], vals=[1.2000000476837158, 3.700000047683716, 8.0, 9.0, nan, 12.0, 7.0, nan]), n_targets=4, nodes_falseleafs=[1, 0, 1], nodes_falsenodeids=[2, 2, 3], nodes_featureids=[0, 0, 0], nodes_modes=make_tensor("value", 2, dims=[3], vals=[0, 6, 6]), nodes_splits=make_tensor("value", 1, dims=[3], vals=[11.0, 232344.0, nan]), nodes_trueleafs=[0, 1, 1], nodes_truenodeids=[1, 0, 1], post_transform=0, tree_roots=[0])
E                                                                                                                                                                                             ^

onnxscript.backend.onnx_export_test.TestOnnxBackEnd::test_export2python_produces_correct_onnx_script_model_0026_test_ai_onnx_ml_tree_ensemble_set_membership

Stack Traces | 0.047s run time

onnxscript\converter.py:460: in _eval_constant_expr
    return eval(cpl, self.globals, locals)  # pylint: disable=eval-used
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
E   NameError: name 'nan' is not defined

The above exception was the direct cause of the following exception:
.nox\test_ort_nightly\Lib\site-packages\parameterized\parameterized.py:620: in standalone_func
    return func(*(a + p.args), **p.kwargs, **kw)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript\backend\onnx_export_test.py:271: in test_export2python_produces_correct_onnx_script_model
    functions = extract_functions(backend_test.name, code, self.test_folder)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript\backend\onnx_export_test.py:137: in extract_functions
    mod = importlib.import_module(import_name)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
C:\hostedtoolcache\windows\Python\3.11.9\x64\Lib\importlib\__init__.py:126: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
<frozen importlib._bootstrap>:1204: in _gcd_import
    ???
<frozen importlib._bootstrap>:1176: in _find_and_load
    ???
<frozen importlib._bootstrap>:1147: in _find_and_load_unlocked
    ???
<frozen importlib._bootstrap>:690: in _load_unlocked
    ???
.nox\test_ort_nightly\Lib\site-packages\_pytest\assertion\rewrite.py:186: in exec_module
    exec(co, module.__dict__)
tests\onnx_backend_test_code\test_ai_onnx_ml_tree_ensemble_set_membership.py:9: in <module>
    @script()
     ^^^^^^^^
onnxscript\main.py:94: in transform
    result = script_check(f_ast, opset, env, src, default_opset=default_opset)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript\main.py:38: in script_check
    return convert.translate_function_def(f)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript\converter.py:1452: in translate_function_def
    fn_ir = self._translate_function_def_common(stmt)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript\converter.py:1439: in _translate_function_def_common
    self._translate_stmt(s, index_of_stmt=i)
onnxscript\converter.py:961: in _translate_stmt
    return self._translate_assign_stmt(node)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript\converter.py:1048: in _translate_assign_stmt
    assign(lhs, rhs)
onnxscript\converter.py:992: in assign
    t = self._translate_expr(rhs, lhs).name
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript\converter.py:546: in _translate_expr
    r = self._translate_call_expr(node)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript\converter.py:825: in _translate_call_expr
    attrs = [
onnxscript\converter.py:826: in <listcomp>
    self._translate_attr(x, y, callee.op_schema.attributes[x])
onnxscript\converter.py:510: in _translate_attr
    val = self._eval_constant_expr(expr)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
onnxscript\converter.py:462: in _eval_constant_expr
    raise NameError(
E   NameError: ERROR: Missing names, globals contains ['__name__', '__doc__', '__package__', '__loader__', '__spec__', '__file__', '__cached__', '__builtins__', '@py_builtins', '@pytest_ar', 'numpy', 'TensorProto', 'make_tensor', 'script', 'external_tensor', 'Opset', 'FLOAT', 'ai_onnx_ml5'], locals [].
E   at: Function 'bck_test_ai_onnx_ml_tree_ensemble_set_membership', line 3
E       Y = ai_onnx_ml5.TreeEnsemble(X, aggregate_function=1, leaf_targetids=[0, 1, 2, 3], leaf_weights=make_tensor("value", 1, dims=[4], vals=[1.0, 10.0, 1000.0, 100.0]), membership_values=make_tensor("value", 1, dims=[8], vals=[1.2000000476837158, 3.700000047683716, 8.0, 9.0, nan, 12.0, 7.0, nan]), n_targets=4, nodes_falseleafs=[1, 0, 1], nodes_falsenodeids=[2, 2, 3], nodes_featureids=[0, 0, 0], nodes_modes=make_tensor("value", 2, dims=[3], vals=[0, 6, 6]), nodes_splits=make_tensor("value", 1, dims=[3], vals=[11.0, 232344.0, nan]), nodes_trueleafs=[0, 1, 1], nodes_truenodeids=[1, 0, 1], post_transform=0, tree_roots=[0])
E                                                                                                                                                                                             ^

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